The Contractor shall exert its best efforts to design, develop, and evaluate speech processors for use with implanted auditory prostheses in deaf humans. An essential component of all auditory prostheses is the speech processor whose function is to convert the wideband electrical signal from the microphone to an information condensed signal or set of signals for driving the individual electrical implant stimulators in a manner to optimize speech recognition by the implant users. The Contractor will pursue efforts to develop laboratory based and wearable speech processing systems; they will devise, evaluate, and refine speech processing techniques using human subjects with previously implanted auditory prostheses; determine processing factors which best relate to speech comprehension in environments with different signal to noise levels, and develop new speech processing strategies using this information. They will also study the effects of learning by using the developed wearable processors in previously implanted patients over an extended testing period.